Floppy interface for Raspberry Pi

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geraldholdsworth
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Floppy interface for Raspberry Pi

Post by geraldholdsworth » Tue Dec 19, 2017 6:13 pm

Hi all,

A while ago I mentioned that my friend, Jasper Renow-Clarke, had designed a board for interfacing a floppy drive to the Raspberry Pi. Well, he has asked me to see if there is any interest in fully populated boards, as he has found someone willing to build them for him. However, he only has four boards left, so first come first served.
Not sure on pricing, but if you PM me, I'll send you Jasper's email address (unless you have it already, of course) and he can negotiate a price with you.

Cheers,

Gerald.
Gerald Holdsworth
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www.reptonresourcepage.co.uk

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lcww1
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Re: Floppy interface for Raspberry Pi

Post by lcww1 » Tue Dec 19, 2017 6:33 pm

Thanks for bringing this to the forum - sounds fab! :D
I'd be very interested - PM sent...

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pau1ie
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Re: Floppy interface for Raspberry Pi

Post by pau1ie » Tue Dec 19, 2017 10:33 pm

I've already got one, (Unpopulated, but it was pretty easy to build, through quite expensive as I ordered two of everything in case I broke anything!)

It is a great piece of kit, and I wish I had a better understanding. It reads discs fine already, and since it reads the flux it should theoretically work on copy protected discs? It only reads 1 or 0, so it is not like the kryoflux, but for the money it is amazing. I also understand it should be possible to make it write to a disc, or even act as a disc device to the BBC Micro (I would love it if this could be made to work!), but there is no software for this yet. It feels like there is huge potential here, so I hope someone cleverer than me is able to help with the software.

Software repo is on github. The designs are also there, so if you miss out on this offer, you can still roll your own.

Bear in mind my understanding could be completely wrong, so check if you are buying for a particular feature I mention, but I am excited about the possibilities of this board!
I'm working on http://bbcmicro.co.uk

crj
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Re: Floppy interface for Raspberry Pi

Post by crj » Tue Dec 19, 2017 11:53 pm

geraldholdsworth wrote:Not sure on pricing
I picked up an unpopulated board and haven't yet stuffed it with components.

If the price is right, I'd happily save myself some hassle by sending it back to have components added. (-8

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myelin
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Re: Floppy interface for Raspberry Pi

Post by myelin » Wed Dec 20, 2017 7:00 pm

I'm interested in a bare board! Will PM you.
SW/EE from New Zealand, now in San Francisco, making BBC/Electron hardware projects for fun.
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ThomasHarte
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Re: Floppy interface for Raspberry Pi

Post by ThomasHarte » Wed Dec 20, 2017 9:34 pm

pau1ie wrote:t reads discs fine already, and since it reads the flux it should theoretically work on copy protected discs? It only reads 1 or 0, so it is not like the kryoflux, but for the money it is amazing.
I think that should make it exactly as useful as the Kryoflux in terms of hardware. You'd just need to do a bit more software work to apply the same level of forensics.

Incidentally, this is exactly the level at which my emulator works, so if you wanted to spec out some sort of trivial file format (e.g. a track-by-track listing of the amount of time between 0<->1 transitions, starting from the index hole) then I could at least give protected disks a try on a virtual Electron. Or tell you what the emulated WD would have said. Or attempt some sort of sufficient BBC emulation further to examine.

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myelin
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Re: Floppy interface for Raspberry Pi

Post by myelin » Wed Dec 20, 2017 10:08 pm

ThomasHarte wrote:I think that should make it exactly as useful as the Kryoflux in terms of hardware. You'd just need to do a bit more software work to apply the same level of forensics.
Looking at the code, it appears to read whole tracks at a time using SPI running at 12.5MHz, so it gets 25 samples per bit time (assuming 500 kbit/s data rate on the disk), which is pretty high res. Should be pretty good for reconstruction!
SW/EE from New Zealand, now in San Francisco, making BBC/Electron hardware projects for fun.
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Re: Floppy interface for Raspberry Pi

Post by ThomasHarte » Wed Dec 20, 2017 10:30 pm

myelin wrote:
ThomasHarte wrote:I think that should make it exactly as useful as the Kryoflux in terms of hardware. You'd just need to do a bit more software work to apply the same level of forensics.
Looking at the code, it appears to read whole tracks at a time using SPI running at 12.5MHz, so it gets 25 samples per bit time (assuming 500 kbit/s data rate on the disk), which is pretty high res. Should be pretty good for reconstruction!
That'd be an even smarter file format I think: just the raw bit stream at an absurd sampling rate. Let an off-the-shelf compressor at it and see where things stand. Probably still large but hopefully not massive.

If anybody is willing to produce such an image, I'd love to get hold of it.

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myelin
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Re: Floppy interface for Raspberry Pi

Post by myelin » Wed Dec 20, 2017 10:57 pm

ThomasHarte wrote:That'd be an even smarter file format I think: just the raw bit stream at an absurd sampling rate. Let an off-the-shelf compressor at it and see where things stand. Probably still large but hopefully not massive.

If anybody is willing to produce such an image, I'd love to get hold of it.
It looks like the bbc-fdc software will do that... it looks like it takes a megabyte of samples per track (three and a bit copies of the track), so you'd end up with a 160MB file for most disks. I won't have time for a week or so, but will see if I can visit my parents' attic and get a disk drive and some of my old Acorn disks, and once I get the Pi hookup sorted out I should be able to produce some samples for you.
SW/EE from New Zealand, now in San Francisco, making BBC/Electron hardware projects for fun.
Most popular: fast serial port, FX2+PiTubeDirect Tube/Cartridge adapter, USB cart interface.

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myelin
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Re: Floppy interface for Raspberry Pi

Post by myelin » Thu Dec 21, 2017 2:28 am

Diverging from the thread topic a bit... I wonder if it would be possible to communicate with a floppy drive using an EZ-USB FX2 (like over in the logic analyzer thread, but using the FX2 to drive the control signals too). It looks like it can happily stream 16-bit samples at 12MHz, so it has the bandwidth to spare.

It looks like floppy drives require pullups on a bunch of lines, so it won't be possible to just wire them directly together to make a prototype, but this is probably worth investigating.
SW/EE from New Zealand, now in San Francisco, making BBC/Electron hardware projects for fun.
Most popular: fast serial port, FX2+PiTubeDirect Tube/Cartridge adapter, USB cart interface.

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pau1ie
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Re: Floppy interface for Raspberry Pi

Post by pau1ie » Fri Dec 22, 2017 8:59 pm

ThomasHarte wrote: If anybody is willing to produce such an image, I'd love to get hold of it.
Sorry for hijacking the thread. I created an image of a copy of Acornsoft Database that I happened to have in ssd and the binary format, which is just the 1s and 0s. I put it in my google drive It was produced using the bbcfdc program in both modes, and I also include the output printed to the screen, which is more verbose and probably interesting in the ssd rip than the binary one. Note that the disc is 40/80 track, and unused parts appear to be unformatted. I hope this is useful.
I'm working on http://bbcmicro.co.uk

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myelin
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Re: Floppy interface for Raspberry Pi

Post by myelin » Tue Jan 02, 2018 9:30 pm

Jasper just posted me a board. I'll document the assembly process when it arrives. He says he's modified BeebEm to be able to take the 160MB raw (double sided 80 track DFS) disk image files, and it's working well. He also has some new code that hasn't made it up to GitHub yet.
SW/EE from New Zealand, now in San Francisco, making BBC/Electron hardware projects for fun.
Most popular: fast serial port, FX2+PiTubeDirect Tube/Cartridge adapter, USB cart interface.

ThomasHarte
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Re: Floppy interface for Raspberry Pi

Post by ThomasHarte » Tue Jan 02, 2018 9:38 pm

myelin wrote:Jasper just posted me a board. I'll document the assembly process when it arrives. He says he's modified BeebEm to be able to take the 160MB raw (double sided 80 track DFS) disk image files, and it's working well. He also has some new code that hasn't made it up to GitHub yet.
You can also expect to see support in the next version of Clock Signal, my current Electron, etc, emulator. I've also been looking into potential sufficiently-mild intermediate containers. Given that each pulse in the captured stream describes the location of a flux transition on the disk, my favourite right now is per-track CSW, being something off-the-shelf that many emulators will already have implemented.

Then I got distracted, but I'll endeavour to follow-through on that line of enquiry shortly.

Thanks a million for the capture!

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myelin
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Re: Floppy interface for Raspberry Pi

Post by myelin » Tue Jan 30, 2018 10:25 pm

I finally got around to assembling mine, and started a thread about the bbc-fdc board in the 8 bit hardware section, where it might get a bit more attention :)
SW/EE from New Zealand, now in San Francisco, making BBC/Electron hardware projects for fun.
Most popular: fast serial port, FX2+PiTubeDirect Tube/Cartridge adapter, USB cart interface.

alienkidmj12
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Re: Floppy interface for Raspberry Pi

Post by alienkidmj12 » Mon Mar 05, 2018 1:17 pm

interested if it can read disks in raw.

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pau1ie
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Re: Floppy interface for Raspberry Pi

Post by pau1ie » Mon Mar 05, 2018 3:35 pm

Yes it can. See my post above.
I'm working on http://bbcmicro.co.uk

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